Memory device having data paths with multiple speeds

ABSTRACT

A memory device has multiple bi-directional data paths. One of the multiple bi-directional data paths is configured to transfer data at one speed. Another one of the multiple bi-directional data paths is configured to transfer data at another speed. The memory device has different modes. Depending on a certain mode, the memory device uses different combinations of the multiple bi-directional data paths to transfer data either at a single speed or at multiple speeds. In some cases, the data represents data information to be stored in memory cells of the memory device. In other cases, the data represents control information and feedback information to be transferred to and from internal circuits, besides the memory cells, of the memory device.

This application is a Divisional of U.S. application Ser. No.10/608,743, filed Jun. 24, 2003 now U.S. Pat. No. 6,961,269, which isincorporated herein by reference.

FIELD

The present invention relates generally to semiconductor devices, moreparticularly to data paths in memory devices.

BACKGROUND

Memory devices reside in many computers and electronic products to storedata. A typical memory device has a data path and many memory cells. Thedata path transfers data to and from the memory cells. Typically, thedata path is designed to transfer data at a specific speed (frequency).This specific speed is the normal speed.

In some situations, transferring data in a memory device at a speeddifferent from the normal speed is preferable. However, in most memorydevices, the data path designed to transfer data at one speed may nottransfer data properly at another speed.

Therefore, transferring data in most memory devices at a speed differentfrom the normal speed may result in an improper operation.

SUMMARY OF THE INVENTION

The present invention provides circuits and methods for transferringdata in a memory device at different speeds in different situations.

One aspect includes a memory device having a memory array, a first datapath, and a second data path. Each of the first and second data paths isa bi-directional data path. The first data path is configured totransfer data to and from the memory array at a first speed. The seconddata path is configured to transfer data to and from the memory array ata second speed. The memory device also includes a number oftransceivers. Each of the transceivers connects to both data paths fortransferring data to and from both data paths. The data representvarious types of data. In some cases, the data represents datainformation to be stored in memory cells of the memory device. In someother cases, the data represents control information and feedbackinformation transferred to and from internal circuits of the memorydevice besides the memory cells.

Another aspect includes a method of transferring data in a semiconductordevice. The method includes transferring data in the semiconductordevice at a first speed via a first bi-directional data path. The methodfurther includes transferring data in the semiconductor device at asecond speed via a second bi-directional data path.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a memory device according to an embodiment of theinvention.

FIG. 2 shows more detail of a portion of the memory device of FIG. 1.

FIG. 3 is a timing diagram showing an example of a low speed writeoperation and a low speed read operation of the memory device of FIG. 1

FIG. 4 is a timing diagram showing an example of a high speed writeoperation and a high speed read operation of the memory device of FIG.1.

FIG. 5 is a timing diagram showing an example of a low speed writeoperation and a high speed read operation of the memory device of FIG.1.

FIG. 6 is a timing diagram showing an example of a high speed writeoperation and a low speed read operation of the memory device of FIG. 1.

FIG. 7 is a block diagram of a data path the memory device of FIG. 1.

FIG. 8 shows a system according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The following description and the drawings illustrate specificembodiments of the invention sufficiently to enable those skilled in theart to practice it. Other embodiments may incorporate structural,logical, electrical, process, and other changes. In the drawings, likenumerals describe substantially similar components throughout theseveral views. Examples merely typify possible variations. Portions andfeatures of some embodiments may be included in or substituted for thoseof others. The scope of the invention encompasses the full ambit of theclaims and all available equivalents.

FIG. 1 shows a memory device according to an embodiment of theinvention. Memory device 100 includes a memory array 101 having memorycells 103 arranged in rows and columns. Row and column decoders 104 and106 provide access to memory cells 103 in response to address signalsA0-AX on address lines (bus) 108. A memory controller 118 controls theoperations of memory device 100 based on control signals on controllines 120. Examples of control signals include a clock signal CLK, a rowaccess strobe signal RAS*, a column access strobe signal CAS*, a writesignal WE*, and a chip select signal CS*.

Memory controller 118 activates certain timing, enable, and selectsignals during various operations of memory device 100. An example of atiming signal includes the WS_(L) and RS_(L) signals. Examples of theenable signals include the TM (0-n), WEN_(H), REN_(H), WEN_(L), andREN_(L) signals. Examples of the select signals include the S_(IN) (0-X)and S_(OUT) (0-Y) signals. Memory controller 118 activates these timing,enable, and select signals based on a certain combination of the signalson lines 120 and lines 108. The functions of these timing, enable, andselect signals are described in connection with subsequent figures.

Memory device 100 further includes two data paths 111 and 122, a pathselector 121, a strobe transceiver circuit 125, and a data transceivercircuit 127. Each of the data paths 111 and 122 is a bi-directional datapath; it transfers data in both ways: to and from memory array 102. Pathselector 121 selects which one of the data paths 111 and 122 to transferdata based on a certain combination of the TM (0-n) signals. Pathselector 121 connects to data path 111 via lines 165 and lines 167 andalso to data path 122 via lines 169. For simplicity, in FIG. 1, some ofthe single lines represent a group of lines. For example, each of thelines 155, 157, 181, 152, 165, 167, and 169 represents a group ofparallel lines.

Strobe transceiver circuit 125 includes write strobe transceivers (WSTTX) 131 (131-0 to 131-M) and read strobe transceivers (RST TX) 141(141-0 to 141-M). Write and read strobe transceivers 131 and 141 arebi-directional circuits; they transfer data in both directions. Thesetransceivers transfer data represented by signals WDQS (0-M) and RDQS(0-M) to and from data paths 111 and 122. Lines 155 and 157 carry datatransferred between strobe transceiver circuit 125 and data path 111.Lines 181 carry data transferred between strobe transceiver circuit 125and data path 122.

Data transceiver circuit 127 includes data transceivers (D TX) 162(162-0 to 162-N). Data transceivers 162 are bi-directional circuits;they transfer data in both directions. Data transceivers 162 transferdata represented by signals DQ (0-N) to and from data path 122. Lines152 carry data transferred between data transceiver circuit 127 and datapath 122.

Lines 161, 171, and 182 correspond to external terminals or connectionsof memory device 100. In some embodiments, lines 161, 171, and 182correspond to pins or solder balls on a packaged integrated circuit ofmemory device 100. In other embodiments, lines 161, 171, and 182correspond to pads on a packaged integrated circuit die of memory device100.

In some embodiments, each of the write strobe transceivers 131, each ofthe read strobe transceivers 141, and each of the data transceivers 162have equal number of elements. In other embodiments, for each element ina transceiver of the transceivers 131, 141, and 162, there is anidentical element in each of the other transceivers. Thus, in theseother embodiments, each of the write strobe transceivers 131, each ofthe read strobe transceivers 141, and each of the data transceivers 162have matched elements. In some other embodiments, each of the writestrobe transceivers 131, each of the read strobe transceivers 141, andeach of the data transceivers 162 have equal number of elements and theelements are matched.

Equal number of matched elements of transceivers within a transceivergroup balances the loads between the transceivers within the transceivergroup. Equal number of matched elements of transceivers among differenttransceiver groups balances the loads among the transceivers ofdifferent groups. Balanced loadings within the same transceiver groupand among different transceiver groups reduce variation among signalstransferred to and from the transceivers, leading to improvedperformance of the memory device.

Memory device 100 can be a dynamic random access memory (DRAM) device.Examples of DRAM devices include synchronous DRAM commonly referred toas SDRAM, SDRAM II, SGRAM (Synchronous Graphics Random Access Memory),DDR SDRAM (Double Data Rate SDRAM), DDR II SDRAM, DDR III SDRAM, GDDRIII SDRAM (Graphic Double Data Rate), and Rambus DRAMs. Memory device100 can also be a static random access memory (SRAM) device, or can be aflash memory. Memory device 100 includes other elements, which are notshown for clarity.

Memory device 100 writes data to memory array 102 in a write operationand reads data from memory array 102 in a read operation. Memory device100 has multiple modes including a test mode and a normal mode. Thewrite operation can be performed either in the test mode or in thenormal mode.

The test mode is a mode in which memory device 100 is put under a testusually during manufacturing of memory device 100. The normal mode is amode in which memory device 100 is not put under a test. An example in anormal mode includes a mode when memory device 100 is used by anend-user. The test mode and the normal mode are selected by a certaincombination of the signals on lines 120 and 108. For example, onecombination of the signals on lines 120 and 108 selects the test modeand another combination of these signals selects the normal mode.

Memory device 100 operates at multiple speeds. In some embodiments, thespeed of memory device 100 is the speed (frequency) of the CLK signal.Thus, in these embodiments, the multiple speeds of memory device 100include the different speeds of the CLK signal. In some embodiments, themultiple speeds include a first speed and a second speed unequal to thefirst speed. For memory device 100 to operate at the first speed, theCLK signal provided to memory device 100 is set at the first speed; andfor memory device 100 to operate at the second speed, the CLK signal isset at the second speed. In some embodiments, the first speed is a lowspeed and the second speed a high speed; the low speed is lower than thehigh speed.

In some embodiments, memory device 100 operates at a speed differentfrom the speed of the CLK signal without resetting or changing the speedof the CLK signal. In these embodiments, memory device 100 includescircuits to internally modify the frequency of the CLK signal. Thecircuits may include a frequency multiplier, or a frequency divider, orboth. The frequency multiplier multiplies the frequency of the CLKsignal to generate an internal clock signal having a frequency higherthan the frequency of the CLK signal. Memory device 100 uses thisinternal clock signal when it operates at a speed higher than the speedof the CLK signal. The frequency divider divides the frequency of theCLK signal to generate an internal clock signal having a frequency lowerthan the frequency of the CLK signal. Memory device 100 uses thisinternal clock signal when it operates at a speed lower than the speedof the CLK signal.

Memory device 100 can operate at the multiple speeds in the test modeand at a single speed in either the test mode or the normal mode. Forexample, memory device 100 can perform the write and read operationseither at the low speed or at the high speed in the test mode and at thehigh speed in the normal mode. Memory device 100 uses many combinationsof data paths 111 and 122 to transfer data to and from memory array 102.

Data path 111 and 122 are configured to transfer data at multiplespeeds. In some embodiments, data path 111 is configured to transferdata at the first speed and data path 122 is configured to transfer dataat the second speed. In some embodiments, memory device 100 uses datapaths 111 and 122 for transferring data at a single speed in both thewrite and read operations. For example, memory device 100 uses data path111 for transferring data at the low speed in both write and readoperations in the test mode, and uses data path 122 for transferringdata at the high speed in both write and read operations in the normalmode. Thus, in both write and read operations in this example, datatransferred in data path 111 in the test mode is slower than datatransferred in data path 122 in the normal mode.

In other embodiments, in the test mode, memory device 100 uses datapaths 111 and 122 for transferring data at multiple speeds. For example,memory device 100 uses data path 111 for transferring data at the lowspeed in the write operation and uses data path 122 for transferringdata at the high speed in the read operation. Thus, in this example, inthe test mode, data transferred in the write operation in data path 111is slower than data transferred in the read operation in data path 122.

As another example, in the test mode, memory device 100 uses data path111 for transferring data at the low speed in the read operation anduses data path 122 for transferring data at the high speed in the writeoperation. Thus, in this example, in the test mode, data transferred inthe write operation in data path 122 is faster than data transferred inthe read operation in data path 111.

In some other embodiments, in the same test mode, memory device 100 usesdata path 111 for transferring data in a first write and read operationsat one speed and uses data path 122 for transferring data in a secondwrite and read operations at another speed. For example, in the sametest mode, memory device 100 uses data path 111 for transferring data ina first write and read operations at the low speed and uses data path122 for transferring data in a second write and read operations at thehigh speed.

Since data path 111 can be configured to operate at a speed lower thanthe speed of data path 122, in some cases such as during the test mode,using data path 111 instead of data path 122 for transferring dataallows for flexibility for controlling and analyzing data during thetest mode.

In this description, data and data signal are used interchangeably. Data(or data signal) represents various types of data including datainformation and timing information. Thus, in one instance, data mayrepresent data information and in another instance, data may representtiming information. Examples of data information include bit values suchas logic one and logic zero representing values of bits of datatransferred to and from memory cells 103 of memory array 102. Otherexamples of data information include certain status values of internalcircuits of memory device 100. Examples of timing information includesignals such as clock signals, strobe signals, and other timing signalsrepresenting time for starting and stopping certain data transfers orcertain operations.

Also in this description, a low speed operation refers to an operationin which memory device 100 performs a certain operation at the lowspeed; and a high speed operation refers to the operation in whichmemory device 100 performs a certain operation at the high speed.

The WDQS (0-M) signals represent both data information and timinginformation. For example, in a low speed read operation, the WDQS (0-M)signals represent data information outputted from data path 111, and ina high speed write operation, the WDQS (0-M) signals represent timinginformation of data signals DQ (0-N) inputted to data path 122.

The RDQS (0-M) signals also represent both data information and timinginformation. For example, in a low speed write operation, the RDQS (0-M)signals represent data information to be transferred to data path 111,and in a high speed read operation, the RDQS (0-M) signals representtiming information of the DQ (0-N) signals outputted from data path 122.

FIG. 2 shows more detail of a portion of the memory of FIG. 1. Writestrobe transceivers 131 have a number of input circuits 213 (213-0 to213-M) and output circuits 233 (233-0 to 233-M). Each of the writestrobe transceivers 131 has a pair of input and output circuitsconnected to each other and also connected to both data paths 111 and122. For example, write strobe transceiver 131-0 has an input circuit231-0 and an output circuit 233-0 connected to each other at one of thelines 161. Input circuit 231-0 also connects to data path 111 and outputcircuit 233-0 also connected to data path 122.

Read strobe transceivers 141 (141-0 to 141-M) have a number of inputcircuits 241 (241-0 to 241-M) and output circuits 243 (243-0 to 243-M).Each of the read strobe transceivers 141 has a pair of input and outputcircuits connected to each other and also connected to both data paths111 and 122. For example, read strobe transceiver 141-0 has an inputcircuit 241-0 and an output circuit 243-0 connected to each other at oneof the lines 171. Input circuit 241-0 also connects to data path 111 andan output circuit 243-0 also connects to data path 122.

Data strobe transceivers 162 (162-0 to 162-N) have a number of inputcircuits 262 (262-0 to 262-M) and output circuits 264 (264-0 to 264-N).Each of the data strobe transceivers 162 has a pair of input and outputcircuit connected to each other and also connected to data path 122. Forexample, data transceiver 162-0 has an input circuit 262-0 and an outputcircuit 264-0 connected to each other at one of the lines 182 and alsoconnected to data path 122.

In some embodiments, input circuits 231, 241, and 262 are identical andoutput circuits 233, 243, and 264 are identical.

Write and read strobe transceivers 131 and 141 have dual functions:transferring data between data path 111 and lines 161 and 171 in oneoperation and transferring data between data path 122 and lines 161 and171 in another operation. Since data path 111 and 122 have differentspeeds, write and read strobe transceivers 131 and 141 transfer data toand from data path 111 at one speed and transferring data to and fromdata path 122 at another speed.

Input circuits 231 of the write strobe transceivers 131 provide inputdata to data path 122. Input circuit 241 of the read strobe transceiversprovide input data to data path 111. Memory device 100 uses the inputcircuits 231 and 241 in different operations. For example, memory device100 uses input circuits 231 to provide signals WS_(H) (0-M) to data path122 during a high speed write operation, and uses input circuits 241 toprovide signals DQW_(L) (0-M) to data path 111 in a low speed writeoperation. The WS_(H) (0-M) signals are high speed write strobe signals.The DQW_(L) (0-M) signals are low speed write data signals.

Output circuits 233 of the write strobe transceivers 131 receive dataoutputted from data path 111. Output circuits 243 of the read strobetransceivers 141 receive data outputted from data path 122. Memorydevice 100 uses output circuits 233 and 243 in different operations. Forexample, memory device 100 uses output circuits 233 to receive signalsDQR_(L) (0-M) from data path 111 in a low speed read operation, and usesoutput circuits 243 to receive signals RS_(H) (0-M) from data path 122during a high speed read operation. The RS_(H) (0-M) signals are highspeed read strobe signals. The DQR_(L) (0-M) signals-are low speed readdata signals.

The WDQS (0-M) signals and the WS_(H) (0-M) signals are the same signalsin one operation and the WDQS (0-M) signals and the DQR_(L) (0-M)signals are the same signals in another operation. For example, whenmemory device 100 performs a high speed write operation, the WS_(H)(0-M) transferred to data path 122 signals are the WDQS (0-M) signalsinputted at lines 161. When memory device 100 performs a low speed readoperation, the WDQS (0-M) signals are the DQR_(L) (0-M) signals providedby data path 111.

The RDQS (0-M) signals and the RS_(H) (0-M) signals are the same signalsin one operation and the RDQS (0-M) signals and the DQW_(L) (0-M)signals are the same signals in another operation. For example, whenmemory device 100 performs a high speed read operation, the RDQS (0-M)signals are the RS_(H) (0-M) signals provided by the data path 122. Whenmemory device 100 performs a low speed write operation, the DQW_(L)(0-M) signals transferred to data path 111 are the RDQ (0-M) signalsinputted at lines 171.

In data transceivers 162, input circuits 262 provide data to data path122 and output circuits 264 receive data outputted from data path 122.Memory device 100 uses input and output circuits 262 and 264 indifferent operations. For example, memory device 100 uses input circuits262 to provide signals DQW_(H) (0-N) to data path 122 during a highspeed write operation, and uses output circuits 264 to receive signalsDQR_(H) (0-N) outputted from data path 122 during a high speed readoperation. The DQW_(H) (0-N) signals are high speed write data signals.The DQR_(H) (0-N) signals are high speed read data signals.

The DQ (0-N) signals and the DQW_(H) (0-N) signals are the same signalsin one operation and the DQ (0-N) signals and the DQR_(H) (0-N) signalsare the same signals in another operation. For example, when memorydevice 100 performs a high speed write operation, the DQW_(H) (0-N)signals transferred to data path 122 are the DQ (0-N) signals inputtedat lines 162. When memory device 100 performs a high speed readoperation, DQ (0-N) signals are the DQR_(H) (0-N) signals provided bydata path 122.

The WS_(L) signal is a low speed write strobe signal. In someembodiments, the WS_(L) represent a plurality of low speed write strobesignals. Memory controller 118 activates the WS_(L) signal during a lowspeed write operation. The WS_(L) signal carries timing information ofthe RDQS (0-M) signals during the low speed write operation. This timinginformation allows data represented by the RDQS (0-M) signals to beaccurately transferred to data path 111 during the low speed writeoperation.

The RS_(L) signal is a low speed read strobe signal. In someembodiments, the RS_(L) signal represents a plurality of low speed readstrobe signals. Memory controller 118 activates the RS_(L) signal duringa low speed read operation. The RS_(L) signal carries timing informationof the WDQS (0-M) signals during a low speed read operation. This timinginformation allows data represented by the WDQS (0-M) signals to beaccurately transferred from data path 111 during the low speed readoperation. The WS_(L) and RS_(L) signals are generated from the clocksignal CLK (FIG. 1). In some embodiments, the RS_(L) signal can beprovided to a pin (pad) of memory device 100 in which the RS_(L) signalmay be in phase with the CLK signal. In other embodiments, the RS_(L)signal is omitted and the CLK signal can be used to carry the timinginformation of the WDQS (0-M) signals during a low speed read operation.

The WDQS (0-M) signals carry timing information of data signals DQ (0-N)signals during a high speed write operation. This timing informationallows data represented by the DQ (0-N) signals to be accuratelytransferred to data path 122 during the high speed write operation.During a low speed read operation, the WDQS (0-M) signals carry datainformation outputted by data path 111.

The RDQS (0-M) signals carry timing information of data signals DQ (0-N)during a high speed read operation. This timing information allows datarepresented by the DQ (0-N) signals to be accurately transferred fromdata path 122 during the high speed read operation. During a low speedwrite operation, the RDQS (0-M) signals carry data information to betransferred to data path 111.

The enable signals WEN_(H), REN_(H), WEN_(L), and REN_(L), generated bymemory controller 118 (FIG. 1), control the input and output circuits ofwrite strobe transceivers 131, read strobe transceivers 141, and datatransceivers 162. Memory controller 118 activates these enable signalsat a certain time based on a particular operation and a particular speedof memory device 100.

The WEN_(H) signal is a high speed write enable signal. The REN_(H)signal is a high speed read enable signal. Memory controller 118activates the WEN_(H) and REN_(H) signals during a high speed operation.

The WEN_(L) signal is a low speed write enable signal WEN_(L). TheREN_(L) signal is a low speed read enable signal. Memory controller 118activates the WEN_(L) and REN_(L) signals during a low speed operation.

FIG. 3 is a timing diagram showing an example of a low speed writeoperation and a low speed read operation of the memory device 100. Thelow speed write operation occurs between times T0 and T1 and low speedread operation occurs between times T1 and T2. In FIG. 3 and also inFIG. 4 through FIG. 6, DATA represents data (data information) andTIMING INFO represents timing information of the corresponding DATA. Forexample, between times T0 and T1, the RDQS (0-M) signals carry datainformation indicated by DATA and the WS_(L) signal carries timinginformation indicated by TIMING INFO. This TIMING INFO carried by theWS_(L) is the timing information corresponding to the DATA carried bythe RDQS (0-M) signals.

Between times T0 and T1, the RDQS (0-M) signals represent input data.These input data are transferred to data path 111 (FIG. 2) as theDQW_(L) (0-M) signals. The low speed write signal WEN_(L) is activated(enabled or HIGH) to allow input circuits 241 (FIG. 2) of read strobetransceivers 141 to transfer data to data path 111. The low speed readsignal REN_(L) is deactivated (disabled or LOW) to deactivate outputcircuits 233 and no data or timing information are carried by the WDQS(0-M), DQR_(L) (0-M), and the RS_(L) signals. The high speed write andread signals WEN_(H) and REN_(H) are deactivated (LOW). Thus, input andoutput circuits 231, 243, 262, and 264 controlled by these signals aredeactivated and no data or timing information are transferred throughthese input and output circuits. FIG. 3 shows that the DQ (0-N), DQW_(H)(0-M), DQR_(H) (0-M), WS_(H) (0-M), and RS_(H) (0-M) signals carry nodata or timing information.

Between times T1 and T2, the WDQS (0-M) signals represent output data.These output data are transferred from data path 111 (FIG. 2) by theDQR_(L) (0-M) signals. The low speed read REN_(L) signal is activated(HIGH) to allow output circuits 233 (FIG. 2) of write strobetransceivers 131 to transfer data from data path 111 to lines 161. TheREN_(L) signal is deactivated (LOW) to deactivate output circuits 241and no data or timing information are carried by the RDQS (0-M), DQW_(L)(0-M), and the WS_(L) signals. The high speed signals remain at theirprevious states. In the low speed write and read operations, no data istransferred between any transceiver and data path 122.

FIG. 4 is a timing diagram showing an example of a high speed writeoperation and a high speed read operation of the memory device 100. Thehigh speed write operation occurs between times T0 and T1. The highspeed read operation occurs between times T1 and T2.

Between times T0 and T1, the DQ (0-N) signals represent input data.These input data are transferred to data path 122 (FIG. 2) as theDQW_(H) (0-N) signals. The WS_(H) (0-M) signals are the same as the WDQS(0-M) signals and are carry timing information of the DQ (0-N) signals.The high speed write WEN_(H) signal is activated to allow input circuits231 (FIG. 2) of write strobe transceivers 131 to transfer the timinginformation to data path 122. The high speed read signal REN_(H) isdeactivated (LOW) to deactivate output circuits 243 and 264 and no dataor timing information are carried by the RDQS (0-M), DQR_(H) (0-N), andthe RS_(H) (0-M) signals. The low speed write and read signals WEN_(L)and REN_(L) are deactivated (LOW). Thus, input and output circuits 233,241, and 243 controlled by these signals are deactivated and no data ortiming information are transferred through these input and outputcircuits. FIG. 4 shows that the RDQS (0-M), DQW_(L) (0-M), DQR_(L)(0-M), WS_(L), and RS_(L) signals carry no data or timing information.

Between times T1 and T2, the DQ (0-N) signals represent output data.These output data are transferred from data path 122 (FIG. 2) by theDQR_(H) (0-N) signals. The RDQS (0-M) signals are the same as the RS_(H)(0-M) signals and are carry timing information of the DQ (0-N) signals.The high speed read REN_(H) signal is activated to allow output circuits243 (FIG. 2) of read strobe transceivers 131 to transfer the timinginformation to lines 171. The high speed write signal WEN_(H) isdeactivated (LOW) to deactivate input circuits 231 and 262 and no dataor timing information are carried by the WDQS (0-M), DQW_(H) (0-N), andthe WS_(H) (0-M) signals. The low speed signals remains at theirprevious states. In the high speed write and read operations, no data istransferred between any transceivers and data path 111.

FIG. 5 and FIG. 6 show other combinations of the write and readoperations of the memory device 100.

FIG. 5 is a timing diagram showing an example of a low speed writeoperation and a high speed read operation of the memory device 100. Thelow speed write operation occurs between times T0 and T1 and is similarto the low speed write operation of FIG. 3. The high speed readoperation occurs between times T1 and T2 and is similar to the highspeed read operation of FIG. 4. In some embodiments, memory device 100performs the operations described in FIG. 5 in a reverse fashion: thelow speed write operation is performed between times T1 and T2 and thehigh speed read operation is performed between times T0 and T1.

FIG. 6 is a timing diagram showing an example of a high speed writeoperation and a low speed read operation of the memory device 100. Thehigh speed write operation occurs between times T0 and T1 and is similarto the high speed write operation described in FIG. 4. The low speedread operation occurs between times T1 and T2 and is similar to the lowspeed read operation described in FIG. 3. In some embodiments, memorydevice 100 performs the operations described in FIG. 6 in a reversefashion: the high speed write operation is performed between times T1and T2 and the low speed read operation is performed between times T0and T1.

FIG. 7 is block diagram of data path 111 of memory device 100. Data path111 includes a select unit 702 connected to an input/output circuit 710and an internal circuit 720. Input/output circuit 710 transfers data toand from memory cells 103 (FIG. 1). Based on select signals S_(IN) (0-X)and S_(OUT) (0-Y), select circuit 702 selects one route from amongmultiple routes to transfer data. The multiple routes include a routebetween strobe transceivers 131 and 141 and input/output circuit 702 anda route between strobe transceivers 131 and 141 and internal circuit720. Internal circuit 720 represents other circuits of memory device 100besides memory cells of memory array 102. In embodiments represented byFIG. 7, internal circuit 720 is shown as a part of data path 111.However, in other embodiments, internal circuit 720 can be outside ofdata path 111 and can be located anywhere within memory device 100.

Select unit 702 has an input select circuit 704 and an output selectcircuit 706. In some embodiments, each of the input and output selectcircuits 704 and 706 has multiplexing circuitry and decoding circuitryfor selecting among the multiple routes. Input select circuit 704transfers data from lines 157 to one of the lines 757A and lines 757Bbased on input select signals S_(IN) (0-X). Output select circuit 706transfers data from one of the lines 755A and 755B to lines 155 based onoutput select signals S_(OUT) (0-Y). Data on lines 155 and lines 157 arethe data transferred to and from write and read strobe transceivers 131and 141 (FIG. 2).

Input/output circuit 710 includes a number of input latches 712 (712-0to 712-M) for receiving data from lines 757A and a number of outputlatches 714-0 to 714-M (714) for outputting data to lines 755A. Acompression and decompression (C/D) engine 716 connects to latches 712and 714 for compressing and decompressing data. In some embodiments, C/Dengine 716 decompresses data received from input latches 712 beforetransferring the data to lines 167 and compresses data received fromlines 165 before transferring the data to output latches 714. Data onlines 165 and 167 are the data transferred to and from memory array 102(FIG. 2). The C/D engine 716 can be activated and deactivated byapplying certain combination of signals on lines 120 and 108 (FIG. 1).

In some embodiments, C/D engine 716 is omitted and no data isdecompressed during transfer between input latches 712 and lines 167 andno data is compressed during transfer between output latches 714 andlines 165.

In other embodiments, C/D engine 716 can be replaced by circuits foroperating on data transferred between input latches 712 and lines 167and between output latches 174 and line 165. For example, C/D engine 716can be replaced by an encryption and decryption engine to encrypt anddecrypt data transferred between input latches 712 and lines 167 andbetween output latches 174 and lines 165. The encryption and decryptionengine can be activated and deactivated by applying certain combinationof signals on lines 120 and 108 (FIG. 1). In some other embodiments, C/Dengine 716 can be replaced by a coding and decoding (CODEC) circuit forcoding and decoding data transferred between input latches 712 and lines167 and between output latches 174 and lines 165. The CODEC circuit canbe activated and deactivated by applying certain combination of signalson lines 120 and 108 (FIG. 1).

Internal circuit 720 includes a control path 722 and a feedback path724. Control path 722 provides control data (signals) on lines 757B tointernal circuit 720 via lines 732. Feedback path 722 provides feedbackdata via lines 734 from internal circuit 720 to lines 755B. For example,during a certain mode such as a test mode, input select circuit 704selects lines 757B to transfer the control data provided by readtransceivers 141. Control path 722 transfers the control data on lines757B to control internal circuit 720 during the test mode. As anotherexample, during a certain mode such as a test mode, output selectcircuit 706 selects lines 755B to transfer feedback data provided byfeedback path 724 collected from internal circuits 720. The feedbackdata may include data representing certain values of the internalcircuits of memory device 100. Write strobe transceivers 131 receive thefeedback data for analysis to determine the performance of the internalcircuits, or the performance of the entire memory device 100.

A different combination of the S_(IN) (0-X) and S_(OUT) (0-Y) signalsselects a different route for transferring data between one of thetransceivers 131 and 141 and one of the circuits 710 and 720. In someembodiments, memory controller 120 chooses a certain combination of theS_(IN) (0-X) and S_(OUT) (0-Y) signals based on the signals on lines 120and lines 108 (FIG. 1).

A first combination of the S_(IN) (0-X) and S_(OUT) (0-Y) signalsselects a route between read strobe transceivers 141 and input/outputcircuit 710. In some embodiments, the first combination of the S_(IN)(0-X) and S_(OUT) (0-Y) signals occurs during a low speed writeoperation in which data from read strobe transceivers 141 are written tomemory array 102 via a route having elements connected by lines 157,757A, and 167.

A second combination of the S_(IN) (0-X) and S_(OUT) (0-Y) signalsselects a route between read strobe transceivers 141 and internalcircuit 720. In some embodiments, the second combination of the S_(IN)(0-X) and S_(OUT) (0-Y) signals occurs during a low speed writeoperation in which control data from read strobe transceivers 141 aretransferred to control path 722 of internal circuit 720 via a routehaving elements connected by lines 157 and 757B.

A third combination of the S_(IN) (0-X) and S_(OUT) (0-Y) signalsselects a route between write strobe transceivers 131 and input/outputcircuit 710. In some embodiments, the third combination of the S_(IN)(0-X) and S_(OUT) (0-Y) signals occurs during a low speed read operationin which data from memory array 102 are read to write strobetransceivers 131 via a route having elements connected by lines 165,755A, and 155.

A fourth combination of the S_(IN) (0-X) and S_(OUT) (0-Y) signalsselects a route between write strobe transceivers 141 and internalcircuit 720. In some embodiments, the fourth combination of the S_(IN)(0-X) and S_(OUT) (0-Y) signals occurs during a low speed read operationin which data from feedback path 724 of internal circuit 720 aretransferred to write strobe transceivers 131 via a route having elementsconnected by lines 755B and 155.

Other combinations of the S_(IN) (0-X) and S_(OUT) (0-Y) signalsdeactivate input and output select circuits 704 and 706 and no data istransferred between write and read strobe transceivers 131 and 141 anddata path 111.

In some other embodiments, a certain combination of the S_(IN) (0-X) andS_(OUT) (0-Y) signals causes data to be transferred only between writeand read strobe transceivers 131 and 141 and data path 122 via lines181.

In some embodiments, data path 122 includes elements similar to theelements of data path 111 shown in FIG. 7. In some of these embodiments,data paths 111 and 122 are configured differently to transfer data atdifferent speeds. Data path 111 and 122 can be configured byconstructing data path 111 with elements that operate properly at onespeed and data path 122 with elements that operate properly at anotherspeed. For example, one method to configure data path 111 involvesconstructing elements of data path 111, such as input latches 712 andoutput latches 714, to operate at a first speed. One method to configuredata path 122 involves constructing elements of data path 122, such aselements that are similar to latches 712 and 714, to operate at a secondspeed. In some embodiments, the first speed is lower than the secondspeed and the second speed is designated as the normal speed. In some ofthese embodiments, the normal speed is the maximum speed at which memorydevice 100 operates properly.

Configuring data paths 111 and 122 with different speeds allows optionsfor memory device to transfer data at multiple speeds in differentsituations. For example, data path 111 can be used for transferring dataat a speed lower than the normal speed in a test; and data path 122 canbe used for transferring data at the normal speed either in a test modeor in the normal mode in which the memory device is used by andend-user.

FIG. 8 shows a system according to an embodiment of the invention.System 800 includes a first integrated circuit (IC) 802 and a second IC804. ICs 802 and 804 include semiconductor devices. In some embodiments,ICs 802 and 804 include processors, controllers, memory devices,application specific integrated circuits, and other types of integratedcircuits. In embodiments represented by FIG. 8, IC 802 represents aprocessor and IC 804 represents a memory device. Processor 802 andmemory device 804 communicate using address signals on lines 808, datasignals on lines 810, and control signals on lines 820. In someembodiments, memory device 804 is implemented as memory device 100 (FIG.1), lines 820 corresponding to lines 120, lines 808 corresponding tolines 108, and lines 810 corresponding to the combination of lines 161,171, and 182.

System 800 of FIG. 8 includes computers (e.g., desktops, laptops,hand-helds, servers, Web appliances, routers, etc.), wirelesscommunication devices (e.g., cellular phones, cordless phones, pagers,personal digital assistants, etc.), computer-related peripherals (e.g.,printers, scanners, monitors, etc.), entertainment devices (e.g.,televisions, radios, stereos, tape and compact disc players, videocassette recorders, camcorders, digital cameras, MP3 (Motion PictureExperts Group, Audio Layer 3) players, video games, watches, etc.), andthe like.

Conclusion

Various embodiments of the invention provide circuits and methods foroperating a memory device at various speeds. The memory device has afirst bi-directional data path and a second bi-directional data path.The first multiple bi-directional data path is configured to transferdata at a first speed. The second bi-directional data path is configuredto transfer data at a second speed. The memory device has differentmodes. Depending on a certain mode, the memory device uses differentcombinations of the first and second bi-directional data paths totransfer data either at a single speed or at multiple speeds.

Although specific embodiments are described herein, those skilled in theart recognize that other embodiments may be substituted for the specificembodiments shown to achieve the same purpose. This application coversany adaptations or variations of the present invention. Therefore, thepresent invention is limited only by the claims and all availableequivalents.

1. A method comprising: selectively transfer data in a first datatransfer and a second data transfer, wherein the first data transferincludes transferring data between a plurality of strobe transceiversand a first bi-directional data path, and wherein the second datatransfer includes transferring data between the same plurality of strobetransceivers and a second bi-directional data path.
 2. The method ofclaim 1 further comprising: selectively transferring data between aplurality of data transceivers and the second bi-directional data path.3. The method of claim 1, wherein transferring data between theplurality of strobe transceivers and the first bi-directional data pathincludes: providing data information from the plurality of strobetransceivers to the first bi-directional data path; and providing datainformation from the first bi-directional data path to the plurality ofstrobe transceivers.
 4. The method of claim 3, wherein transferring databetween the plurality of strobe transceivers and the secondbi-directional data path includes: providing timing information from theplurality of strobe transceivers to the second bi-directional data path;and providing data information from the second bi-directional data pathto the plurality of strobe transceivers.
 5. The method of claim 1,wherein the first data transfer is performed at a first speed and thesecond data transfer is performed at a second speed.
 6. A methodcomprising: selecting a first transfer route of a first data path totransfer data at a first speed from a read strobe transceiver to amemory cell; selecting a second transfer route of the first data path totransfer data at the first speed from the memory cell to a write strobetransceiver; selecting a second data path to transfer data at a secondspeed between a data transceiver and the memory cell; and selecting anadditional transfer route to transfer data at the second speed betweenthe second data path and one of the read and write strobe transceivers.7. The method of claim 6, wherein selecting the first transfer routeincludes applying a first combination of select signals to the firstdata path.
 8. The method of claim 7, wherein selecting the secondtransfer route includes applying a second combination of the selectsignals to the first data path.
 9. The method of claim 8, whereinselecting the second data path includes applying a third combination ofthe select signals to the first data path.
 10. A method comprising:transferring data at a first speed from a read strobe transceiver to amemory cell via a first transfer route of a first data path;transferring data at the first speed from the memory cell to a writestrobe transceiver via a second transfer route of the first data path;transferring data at a second speed between a second data path and oneof the read and write strobe transceivers; selecting a first transferroute of the second data path to transfer data at the second speed froma data transceiver to the memory cell; and selecting a second transferroute of the second data path to transfer data at the second speed fromthe memory cell to the data transceiver.
 11. The method of claim 10,wherein transferring data at a first speed from the read strobetransceiver includes applying a first combination of select signals tothe first data path.
 12. The method of claim 11, transferring data atthe first speed from the memory cell includes applying a secondcombination of the select signals to the first data path.
 13. The methodof claim 12, wherein selecting one of first and second the transferroute of the second data path includes applying a third combination ofthe select signals to the first data path.
 14. A method comprising:selecting a first transfer route of a first data path to transfer dataat a first speed from a read strobe transceiver to a memory cell of amemory device; selecting a second transfer route of the first data pathto transfer data at the first speed from the memory cell to a writestrobe transceiver; selecting a third transfer route of the first datapath to transfer data at a first speed from the read strobe transceiverto an internal circuit of the memory device; selecting a fourth transferroute of the first data path to transfer data at the first speed fromthe internal circuit to the write strobe transceiver; and transferringdata at a second speed between a second data path and the memory celltransferring data at the second speed between the second data path andone of the read and write strobe transceivers.
 15. The method of claim14, wherein selecting one of the first transfer route, the secondtransfer route, the first transfer route, and the fourth transfer routeincludes applying a first combination of select signals to the firstdata path.
 16. The method of claim 15, wherein transferring data at thesecond speed includes applying a second combination of the selectsignals to the first data path.
 17. A method comprising: transferringdata at a first speed from a read strobe transceiver to a memory cell ofa memory device via a first transfer route of a first data path;transferring data at the first speed from the memory cell to a writestrobe transceiver via a second transfer route of the first data path;transferring data at a first speed from the read strobe transceiver toan internal circuit of the memory device via a third transfer route ofthe first data path; transferring data at the first speed from theinternal circuit to the write strobe transceiver via a fourth transferroute of the first data path; transferring data at a second speedbetween a second data path and one of the read and write strobetransceivers; selecting a first transfer route of the second data pathto transfer data at the second speed from a data transceiver to thememory cell; and selecting a second transfer route of the second datapath to transfer data at the second speed from the memory cell to thedata transceiver.
 18. The method of claim 17, wherein transferring dataat the first speed via one of the first transfer route, the secondtransfer route, the first transfer route, and the fourth transfer routeincludes applying a first combination of select signals to the firstdata path.
 19. The method of claim 18, wherein selecting one of firstand second the transfer route of the second data path includes applyinga second combination of the select signals to the first data path.